TDS on Ocean Freight U/s.195

Hi,

I would like to whether tax is deductible in respect of payment made to a Non-resident towards freight in case of,

a) consignment from outside the India to India,

b) consignment from India to Outside the Country.

Please clarify with reference to DTAA

Would also like to know, how the above transactions are effected by the provisions of Section 172.

Thanks in Advance

Dharmaraju